The availability of a means to permit a swimmer to rest in a comfortable sitting position in a stable seat within a swimming pool has become increasingly desirable especially for more elderly swimmers who desire to rest temporarily while still remaining in the swimming pool. While it is of course possible to lower a chair or stool into the swimming pool as a seating means, this is awkward and generally uncomfortable and unsatisfactory and, sometimes, even hazardous when the seat becomes dislodged. Various schemes devised to afford seating arrangements within or adjacent to the pool, such as those chair units shown in U.S. Pat. Nos. 4,468,822 and 4,837,869, or arrangements that comprise a therapy unit (which may include a seating arrangement ), have been proposed. Other arrangements previously tried include: a permanent integrated installation of seats such as that disclosed in my co-pending patent application, Ser. No. 07/869,737. filed on Apr. 10, 1892; placing a therapy pool contiguous or within a swimming pool; attaching the therapy pool to the wall of the swimming pool with a transition section as disclosed, for example, in U.S. Pat. No. 4,001,899; and the arrangement of depositing a removable partition comprising a therapy pool within the swimming pool as disclosed in U.S. Pat. No 4,240,165. However, a need exists for a conveniently adaptable retrofit seating unit for existing swimming pools that is reliable, economical and practical such as that provided by the present invention.